Dimensionality and Interface Engineering of 2D Homologous Perovskites for Boosted Charge-Carrier Transport and Photodetection Performances.

Two-dimensional (2D) homologous halide perovskite (HP) microcrystallines have emerged as a promising alternative light-sensitive material; however, the undesirable quantum confinement effect and severe interfacial charge-carrier scattering still hamper their applications in photodetectors (PDs). Here we propose a novel postsynthetic treatment to simultaneously solve both problems. 2D (OA)FAPbBr (OA and FA represent octadecylamine and formamidine) microplatelet film was immersed in solution containing FA, leading to improvements in two aspects. First, the dimensionality of 2D HPs was increased through an exchange reaction between OA and FA, which meliorates the quantum confinement effect and facilitates the separation of electrons and holes; second, the free-standing 2D HP microcrystallines were fused for promoted interdomain charge-carrier transport. The treated PDs achieved a 3600 and 4200% increase in external quantum yield and responsivity up to 7100% and 32 A/W, respectively, and the rise/decay time was shortened by two orders of magnitude to 0.25/1.45 ms.